function sys=obv(t,x,dt,y1)
sys=zeros(2,1);

eps=1;k1=24.27;k2=5;
x1=x(1);x2=x(2);

sys(1)=eps*(y1-(y1^3)/3+dt)+x2-k1*abs(x1-y1)*sign(x1-y1);
sys(2)=-y1-k2*sign(x1-y1);